Fire extinguishing system for cook stoves and ranges

ABSTRACT

An automatic fire extinguishing system for a cooking range having top burners includes a hood mountable over the range. A tank containing fire extinguishing fluid is removably mounted in the hood. The tank has a solenoid operated valve connected in circuit with a thermostat and power line to discharge fluid from the tank when the thermostat is operated. The range may have electric or gas burners. A solenoid operated switch or solenoid operated valve is connected in circuit with the thermostat to open the power line to the electric burners or to open the gas main to the gas burners when the thermostat operates. An automatically operated exhaust fan and alarm are also provided. The system includes manually operable set and reset switch means.

United States Patent Dockery [451 Apr. 4, 1972 [54] FIRE EXTINGUISHINGSYSTEM FOR COOK STOVES AND RANGES [72] Inventor: Walter E. Dockery, 2120La Vera Dr.,

Tuscaloosa, Ala. 35401 [22] Filed: Sept. 25, 1970 [21] Appl. No.1 75,403

[52] US. Cl. ..169/2 R, 169/19, 169/23 3,242,652 3/1966 Malenchini169/19 X Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-EdwinD. Grant AttorneyPolachek & Saulsbury [5 7] ABSTRACT An automatic fireextinguishing system for a cooking range having top burners includes ahood mountable over the range. A tank containing fire extinguishingfluid is removably mounted in the hood. The tank has a solenoid operatedvalve connected in circuit with a thermostat and power line to dischargefluid from the tank when the thermostat is operated. The range may haveelectric or gas burners. A solenoid operated switch or solenoid operatedvalve is connected in circuit with the thermostat to open the power lineto the electric burners or to open the gas main to the gas burners whenthe thermostat operates. An automatically operated exhaust fan and alarmare also provided. The system includes manually operable set and resetswitch means.

9 Claims, 5 Drawing Figures Patented April 4, 1972 3,653,443

2 Sheets-Sheet 1 FIRE GXTINGIJ H R 3O .28 SI 46 48 37 36 INVENTOR.WALTER E. DOCKERY ATTURNE Patented April 4, 1972 2 Sheets-Sheet 2EMERGENCY FAN SWITCH TO POWER SUPPLY GAS IURNERS A GAS MAIN IOOA INVENTOR. WALTER E. DOCKERY 9?7 A TTURNEY5 FIRE EXTINGUISHING SYSTEM FORCOOK STOVES AND RANGES This invention relates to an automaticallyoperated fire extinguishing system for an electric or gas cook stove orrange, and particularly concerns such a system associated with a hoodover the stove or range.

Automatic fire extinguishing systems heretofore known for use inconjunction with cook stoves and ranges have generally been concernedwith extinguishing a fire due to burning fat or grease in a pot orkettle. The system was solely concerned with extinguishing the fire andno provision was made for turning off the electric or gas burners of thestove. Frequently the fire extinguishing system extinguished the lightedburners of a gas stove which created a very hazardous condition bypermitting fuel gas to flow freely from the burners. Where the systemextinguished the fire on an electric stove, the burners were leftenergized to reignite spilled grease and fat. No provision was made forautomatically exhausting smoke and fumes generated during the fire andwhile it was being extinguished. No provision was made for sounding analarm. Inadequate provision was made operating the entire systemmanually in lieu of or in addition to automatic operation.

The present invention is directed at overcoming the above and othershortcomings, deficiencies, objections, and disadvantages of priorsystems employed for extinguishing kitchen fires on stoves and rangesand in hoods over the stoves.

According to the present invention a removable and rechargeable fireextinguisher is installed in a hood over an electric or gas range in akitchen. Strategically located thermostats on the hood are connected ina circuit with a circuit breaker for the electric lines energizing theburners of the electric range. Where a gas stove is employed, thethermostats are connected in circuit with a solenoid operated valve forturning off the gas supply to the stove. Also connected in circuit withthe thermostats is a solenoid operated valve which turns on the fireextinguisher to discharge a gaseous or liquid fire extinguishing agentaround the hood and on the stove or range. Suitable agents for thispurpose are described in U.S. Pat. No. 3,463,233. An exhaust fan'may beprovided in the system arranged to turn on automatically for exhaustingfumes and smoke. An automatically operated audible alarm may also beprovided. a

It is therefore a principal object of the invention to provide a fireextinguishing system for a kitchen stove or range in which a fireextinguisher is mounted in a hood over the stove or range.

Another object is to provide a system as described, with thermostatsconnected in circuit with the fire extinguisher to turn it onautomatically, and further connected in circuit with a solenoid operatedswitch or valve for turning off or opening the power or fuel lineenergizing the burners of the stove or range.

A further object is to provide a fire extinguishing system as describedwith means for automatically operating an exhaust fan in the event afire to draw off smoke after the fire is extinguished, and with meansfor operating a fire alarm.

Other and further features, objects and advantages of the invention willbecome apparent from the following detailed description taken togetherwith the drawings, wherein:

FIG. 1 is a perspective view of a hood over a cooking stove or rangeprovided with a fire extinguishing system according to the invention.

FIG. 2 is a bottom plan view of the hood taken on line 2-2 of F IG. 1.

FIG. 3 is a vertical sectional view taken on line 3-3 of FIG.

FIGS. 4 and 5 are diagrams of electrical control circuits used inconnection with fire extinguishing systems for electric and gas rangesrespectively.

Referring first to FIGS. 1-2, there is shown a stove or range havingburners 12 on top 14. This may be an electric range having burnercontrol rheostats 16 on the top of the range. Over the range on kitchenwall 18 is a hood 20. This hood has a downwardly and forwardly slantedtop wall 22, a wide, vertical rear wall 23, vertical trapezoidal sidewalls 24, 26 and a vertical, narrow front wall 28. The hood is open atthe bottom. Mounted inside the hood on brackets 30 is a tank 32containing fire extinguishing fluid 34. The fluid is contained underpressure in a known manner. Extending around the inside walls of thehood near the open bottom is an endless pipe 36, supported on brackets37. This pipe is arranged as a rectangular ring as clearly shown in FIG.2. The pipe is connected to the tank 32 via a flexible conduit 38 andfittings 40, 42. Fitting 40 is joined to a solenoid operated valve 44 atthe head of the tank. Fitting 42 is joined to pipe 36. When valve 44 isoperated the fire extinguishing fluid is discharged into pipe 36. Pipe36 is provided with bottom holes 46 for spraying the fire extinguishingfluid on the top 14 of range 10. Further holes 48 are provided at innersides of the pipe to spray fluid 34 laterally inside the hood.

Thermostats 49 are located at forward outside corners of the hood.Another thermostat 50 is located inside the hood at rear wall 23. A duct52 is provided at the top of the hood. In this duct is an exhaust fan 54located in an exhaust path leading from the hood to chimney pipe 56inkitchen wall 18. Control switches 58 and 60 for the fan are provided onthe from of duct 52. A removable filter or screen 61 is mounted on pipe36 just below tank 32.

A manually operable RESET switch 62 is located at side wall 26 of thehood. A circuit breaker 63 is connected in circuit with the power supplyline 65 for burners 12 as explained below in detail in connection withFIG. 4. Another manually operated switch 64 is provided on wall 18 forturning on the fire extinguishing system manually. An electricallyoperated audible alarm 66 may also be provided for the system. Thisalarm has a control switch 67.

FIG. 4 shows schematically a control circuit in which parts shown inFIGS. 1 and 2 are connected. Power line 65 includes wires 102, 104connected via double pole switch 106 to burners 12 which are in seriesrespectively with rheostats 16. The double-pole switch 106 is normallyclosed but can be opened by plunger 108 of solenoid operated circuitbreaker 63. The solenoid 110 of the circuit breaker is connected atopposite ends to contacts 112, 113 of a relay 114. Contacts 112, 113 arenormally open with respect to contacts 115, 116. Contacts 115, 116 areconnected to wires 104 and 102 respectively. Coil 118 of relay 114 isconnected to wire 104 and to terminal 120 of normally closed RESETswitch 62. This is a pushbutton switch. Terminal 122 of this switch isconnected to contact 124 of relay 114. This contact is normally openwith respect to contact 125 which is connected to power wire 102. Alsoconnected to relay contacts 112, 113 are opposite ends of solenoid 126which operates the valve 44 at the end of tank 32 for discharging fluidinto apertured pipe 36.

A time delay relay 130 has a coil 132 connected to relay contacts 112,113. The relay has contact 133 connected to relay contact 112. Contact134 is connected to one terminal of fan motor 136. The other terminal ofthe fan motor is connected via switch 60 to relay contact 113. Theterminals of the fan motor are also connected via wires and double-poleswitch 58 to power wires 102, 104. Audible alarm 66 is connected at oneend via switch 67 to relay contact 113. The other terminal'is connectedto relay contact 112. Thermostats 49 and 50 are connected in parallel.Open contacts are connected to wire 102. Bimetallic elements 152 areconnected to relay coil 118.

The manually operable emergency set switch 64 is a normally opendouble-pole switch between power wires 102, 104 and points P1, P2 towhich are connected solenoids 110, 126, alarm 66 and relay 130. Closureof switch 64 bypasses relay 114 to operate the system instantly undermanual control regardless of the open or closed condition of thermostats49, 50.

In operation of the system including circuit 100, relay 118 is normallydeenergized and switch 64 is open. Switch 106 is closed. This enablesoperation of the burners 12 in a normal way without interference by thefire extinguishing system. If a fire occurs on the stove or range 10,any one or all of the thermostats 49, 50 will be heated to its operatingtemperature which isabove the highest temperature encountered above therange during normal operation. Closure of any thermostat applies powerto relay coil 118. This relay closes and is held closed via its holdingcircuit including closed contacts 124, 125 and RESET switch 62. Thuseven if the thermostats subsequently open, relay 114 will remainenergized. Closure of relay contacts 112, 115 and 113, 116 energizessolenoid 126 and the valve 44 is operated to discharge fireextinguishing fluid into pipe ring 36 which sprays the fluid on the topof the range and across the hood. Closure of the contacts of relay 114also actuates alarm 66 and this alarm sounds. Closure of the contacts ofrelay 114 also energizes relay 130. This relay has a time delay of 5 tominutes to allow time for the fire extinguisher to extinguish the fire.Then the relay closes and the fan motor is turned on to clear thekitchen of smoke and fumes.

It is possible to omit alarm 66 if this component is not desired. Also,the alarm can be turned off if it is automatically operated by openingswitch 67, or the alarm can be initially deactivated by opening switch67.

It is possible to omit the exhaust fan 54, in which case motor 136 andrelay 130 can be omitted. Where the fan is provided it is possible toturn the fan on manually at any time. This can be -fdone by closingswitch 58 manually. If the fan operates auto- ,"matically, switch 60 canbe opened manually to stop the fan,

- or switch 60 can be left open to deactivate the fan motor.

i' Once the relay 114 is energized, the fire extinguisher discharges itscontents until exhausted. Switch 106 is opened by circuit breaker 63 andremains open. The fan and alarm also stay on. The system can bedeactivated entirely by momentarily pressing the RESET switch 62 to openit. This will open the holding circuit for relay 114. As a safetyprovision the system will automatically operate again if any one of thethermostats 49, 50 is closed, indicating excessive temperature in thehood or over the range 10.

If an attendant happens to be present when a fire breaks out, theemergency switch 64 can be closed manually should relay 114 fail tooperate for any reason, or should thermostats 49, 50 fall to respond atonce. This will apply power to solenoids 110 and 126, and to relay 130and alarm 66 independently ofthe relay 114.

The circuit 100A shown in FIG. 5 is similar to circuit 100 except thatsolenoid operated valve 160 is provided for opening gas main 162automatically in case of a fire on the range where gas burners 12acontrolled by hand valves 16a are installed. All parts mounted in thehood 20 shown in FIG. 1 apply equally well to circuit 100A, so thatparts of circuit 100A corresponding to those of circuit 100 areidentically numbered. Power to operate the system is provided via wires102, 104.

Valve 160 has a solenoid 110a which actuates plunger 108a of the valve.The solenoid is energized by operation of relay 114 in the same manneras described above. Solenoid 126 which operates valve 44 of tank 32, thefan motor 136, alarm 66, the time delay relay 130 and thermostats 49,50all operate as described above. Emergency switch 64 is provided tooperate the system manually when necessary.

The systems described are adapted for installation in kitchens ofhouseholds, restaurants, hotels, hospitals, etc. The systems are adaptedfor operation automatically in the absence of or in the presence of anattendant. However, they also have provisions for manual operation. Thesystems can be installed on hoods of existing ranges with very minoralterations, or they can be installed as original equipment when newlymanufactured. They fulfill a long felt need for automatic effectiveprotection against fire at kitchen ranges and stoves.

While a limited number of embodiments of the invention have beendescribed this has been by way of example only.

Many modifications and variations are possible without departing fromthe invention.

What is claimed is: I 1. An automatic fire extinguishing system for acooking range having top burners comprising a hood mountable over therange, said hood having a closed top, vertical side walls and an openbottom; a tank containing fire extinguishing fluid removably disposedinside the walls of the hood; a solenoid operated valve on said tank forreleasing said fluid when the solenoid is energized; at least onethermostat set to operate at a predetermined temperature and disposedfor sensing the temperature of a fire between the range and hood; anelectric power line; and circuit means interconnecting the thermostat,

rectangular ring inside the hood and connected to said tank via saidvalve for spraying said fluid on the range and across the hood.

3. An automatic fire extinguishing system as defined in claim 1, whereinsaid range includes electric burners, said system further comprisingswitch means connected in said power line for cutting off power suppliedto the burners, and another solenoid connected in said circuit andarranged to open said switch means when the first named solenoid isenergized by operation of said thermostat.

4. An automatic fire extinguishing system as defined in claim 3, furthercomprising relay means in said circuit connected between the power lineand both solenoids and arranged for energizing the solenoids and keepingthe solenoids energized regardless of the temperature sensed by thethermostat after the thermostat is once operated; and reset switch meansconnected in circuit with said relay means for resetting the same todeenergized condition and for deenergizing the solenoids to close thefirst named switch means and to close said valve on the tank.

5. An automatic fire extinguishing system as defined in claim 1, furthercomprising reset switch means connected in circuit with said relay meansfor resetting the same to deenergized condition and for deenergizingsaid solenoid.

6. An automatic fire extinguishing system as defined in claim 5, furthercomprising a motor driven fan arranged to draw fumes and smoke from thehood; and time delay relay means connected in circuit with said firstnamed relay means and said fan for operating the fan only after apredetermined time has elapsed following operation of said solenoid todischarge said fluid from said tank.

7. An automatic fire extinguishing system as defined in claim 6, furthercomprising an alarm connected in circuit with the first named relaymeans for actuation thereby when said first relay means is energized.

8. An automatic fire extinguishing system as defined in claim 1, whereinsaid range includes gas burners and a gas main connected to saidburners, said system further comprising another solenoid operated valveconnected in said circuit and arranged to close said gas main when thefirst named solenoid is energized by operation of said thermostat.

9. An automatic fire extinguishing system as defined in claim 1, furthercomprising reset switch means connected in said circuit for deenergizingsaid solenoid after the same has become energized; and manually operableset switch means connected in said circuit and arranged to energize saidsolenoid independently of the temperature sensed by said thermostat.

1. An automatic fire extinguishing system for a cooking range having topburners comprising a hood mountable over the range, said hood having aclosed top, vertical side walls and an open bottom; a tank containingfire extinguishing fluid removably disposed inside the walls of thehood; a solenoid operated valve on said tank for releasing said fluidwhen the solenoid is energized; at least one thermostat set to operateat a predetermined temperature and disposed for sensing the temperatureof a fire between the range and hood; an electric power line; andcircuit means interconnecting the thermostat, solenoid and power linefor actuating the valve when the thermostat operates upon the occurrenceof a fire between the range and hood, and relay means in said circuitconnected between the power line and said solenoid and arranged forenergizing the solenoid and keeping the solenoid energized regardless ofthe temperature sensed by the thermostat after the thermostat is onceoperated.
 2. An automatic fire extinguishing system as defined in claim1, further comprising an apertured pipe arranged as a rectangular ringinside the hood and connected to said tank via said valve for sprayingsaid fluid on the range and across the hood.
 3. An automatic fireextinguishing system as defined in claim 1, wherein said range includeselectric burners, said system further comprising switch means connectedin said power line for cutting off power supplied to the burners, andanother solenoid connected in said circuit and arranged to open saidswitch means when the first named solenoid is energized by operation ofsaid thermostat.
 4. An automatic fire extinguishing system as defined inclaim 3, further comprising relay means in said circuit connectedbetween the power line and both solenoids and arranged for energizingthe solenoids and keeping the solenoids energized regardless of thetemperature sensed by the thermostat after the thermostat is onceoperated; and reset switch means connected in circuit with said relaymeans for resetting the same to deenergized condition and fordeenergizing the solenoids to close the first named switch means and toclose said valve on the tank.
 5. An automatic fire extinguishing systemas defined in claim 1, further comprising reset switch means connectedin circuit with said relay means for resetting the same to deenergizedcondition and for deenergizing said solenoid.
 6. An automatic fireextinguishing system as defined in claim 5, further comprising a motordriven fan arranged to draw fumes and smoke from the hood; and timedelay relay means connected in circuit with said first named relay meansand said fan for operating the fan only after a predetermined time haselapsed following operation of said solenoid to discharge said fluidfrom said tank.
 7. An automatic fire extinguishing system as defined inclaim 6, further comprising an alarm connected in circuit with the firstnamed relay means for actuation thereby when said first relay means isenergized.
 8. An automatic fire extinguishing system as defined in claim1, wherein said range includes gas burners and a gas main connected tosaid burners, said system further comprising another solenoid operatedvalve connected in said circuit and arranged to close said gas main whenthe first named solenoid is energized by operation of said thermostat.9. An automatic fire extinguishing system as defined in claim 1, furthercomprising reset switch means connected in said circuit for deenergizingsaid solenoid after the same has become energized; and manually operableset switch means connected in said circuit and arranged to energize saidsolenoid independently of the temperature sensed by said thermostat.